C.F. Tsang

Effect of Air Supply Temperature on the Performance of Displacement Ventilation (Part I) - Thermal Comfort

The effect of the air supply temperature on the performance of a displacement ventilation (DV) system has been investigated. The study looks into the case of a typical office building in Hong Kong, under local thermal environment and airflow conditions. These are characterised by the high cooling load density, which commonly occurs in Hong Kong. The lower supply temperatures were found to result in higher draft effects, yet increasing temperatures leads to an increase in the predicted percentage of dissatisfied people (PPD). The DV system was found to provide acceptable thermal comfort at certain air supply temperatures. The levels of PPD could be marginal should the parameters of the system not be optimised.

Validation of a CFD Model for Research into Stratum Ventilation

Abstract In this paper experimental results are used to verify and validate a computational fluid dynamics (CFD) model based on a commercial package. The validation is used to ensure that the CFD model is able to simulate stratum ventilation. The low speed air jet is the basis for a newly proposed ventilation mode whereby jets are placed strategically around a room at breathing height level to create a layer or stratum of relatively fresher air. Case studies from three independent experiments are simulated using the CFD model to ensure that the model is able to represent the physical characteristics, such as air flow and heat transfer properties, of this type of ventilation system.

Stratum Ventilation for a Workshop under Elevated Indoor Temperature

Abstract The performance of stratum ventilation, a recently developed ventilation strategy, is assessed in terms of thermal comfort and indoor air quality using experimental and computational fluid dynamics (CFD) techniques. The case of a typical Hong Kong workshop under local thermal boundary conditions is used to examine the ventilation system. Various factors including percentage dissatisfied (PD) and mean air age/CO2 were computed to determine the system performance. The stratum ventilation is shown to produce improved indoor air quality and thermal comfort for this particular case study.